[Strawbale] Overhead bales

[Chris Green]

Stone Tool wrote:
> Has anybody tried using strawbales between ceiling joists like you would 
> glass bats?  
Some have, but I doubt it's a good practice. The bales could become 
moisture traps.

A much better way might be to coat the straw with a clay slip, let it 
get fairly dry, then pack it into the ceiling. The mix is known as 
leichtlehm ("light loam") in German.

 See this link for more info ( cntl, F and search for leichtlehm )
http://www.strawbalecentral.com/techniques3.html

This is a traditional method which has been used in Europe since time 
began...or at least since people started building houses there...and it 
works quite well as long as the building has a good hat/ good roof. Some 
of these ceilings have been in place for 500 years (according to a 
friend who lived for a while in a cob house at least that old in England.) 

This type of mix has also been used in daub and wattle walls in Europe 
and in the Americas.

In Germany there are laws which stipulate that heritage houses with 
light straw/ clay insulation  in the ceilings have to be restored with 
the same type of insulation. 
<http://www.strawbalecentral.com/techniques3.html>

If the clay has a high proportion of Bentonite in it and some water does 
reach it, the bentonite will expand and create a practical water 
resistant seal, helping to preserve the straw.
A good clay coating should prevent most of the oxygen from reaching the 
straw, thereby preserving the straw, or so I believe. And it reduces the 
risk of fires. (Adding some borax/ Boraxo  should help make them mix 
even more fire resistant and fairly mold proof, btw. And insects will 
stay out of the stuff. )

The weight might require stronger joists and or trusses to support the 
load, but so would bales. With the leichtlehm, you can fill the spaces 
not covered by straight bales, and wrap it around the joists, etc., 
thereby not leaving 'holes' in the insulation layer.

Cheers,

Chris Green.